1. Field of the Invention
The present invention relates generally to the construction of filament wound blades and more particularly to an economical method of constructing such blades for carrying high centrifugal loads, such as those used in the fan blades of jet engines.
2. Description of the Prior Art
It has been common practice to employ metal fan blades in the fan section of jet engines used in aircraft propulsion. With the popularity of larger and larger jet aircraft, it has been necessary to improve the performance of such jet engines and, in so doing, such engines have become larger and larger, the fan sections thereof now commonly having radii of 20 inches or more. As the radii of such jet fan sections increase, the length of the fan blades must also increase, thus increasing the weight thereof and, consequently, the centrifugal forces experienced thereby during high speed operation. Such heavy blades then require extremely massive hubs to withstand the centrifugal forces applied thereto, thus compounding the difficulties created by the increased jet engine size. Overlying these problems are the requirements for quieter operation imposed by various airport authorities. Efforts have been made to minimize the erosion caused by rain passing through the high speed blades and to improve the impact resistance of such blades to reduce damage resulting from debris passing therethrough during operation. While composite blades have been proposed, the excessively high cost of manufacture thereof has never been effectively attached and since hand layup thereof is economically unfeasible, the problem of a feasible manufacture method has never been solved.